Seleucus I Nicator was one of the Diadochi, the rival generals, relatives, and friends of Alexander the Great who fought for control over his empire after his death.
Serving as an infantry commander under Alexander, he eventually gained control of the satrapy of Babylon. From there, he expanded his dominions to include much of Alexander's near-eastern territories.
He founded the Seleucid Empire, which would become a major center of Hellenistic culture. He founded many cities, including Antioch and Seleucia.